Apparatus for generating periodic impulses in a pressure line



Jan. 28, 1964 AKE KARSBERG 3,119,366

APPARATUS FOR GENERATING PERIODIC IMPULSES m A PRESSURE LINE Filed Jan. 10, 1961 To BRAKE L [IVE United States Patent 3,119,366 APPARATUS FQR GENERATING PEREQDIC a HWPULSES lhl A PRESFYURE LTNE Alre Karsherg, 25 Tiadervagen, Bromine, Sweden Filed Jan. 1d, 1961, Ser. No. 81,825 2 Claims. ($1. li655) This invention pertains to pressure indicating systems and more particularly to systems for indicating continuity in a pressure line.

It is of great importance for the safety of operation on railways that the engineer of a train is able to know that the brake system of the train is ready for function. The present invention relates to a system for satisfying this requirement for trains equipped with air brakes in which the engine and all cars on the train are equipped with either air brakes or at least with an air line for connecting cars equipped with brakes.

It is important for safety that a brake test be performed before the departure of the train for preventing the occurrence of an accident, caused by the fact that the brake system does not function. It might, however, also happen that the brake system is put out of action while the train is running, without the engineer observing it immediately. It may for instance happen that an object slips down from a car and, in falling to the ground, strikes a stop cock in the brake line of the train so as to close it. If this cock is located at the end wall of the vehicle, the part of the train being behind this wall will be braked, but the remainder will not. Under disadvantageous conditions, the train part thus being braked may be torn away from the other part of the train, and this incident will not necessarily be observed by the engineer.

Summing up, as long as the engineer is in his cab, and irrespective of the fact whether the train is at a standstill or in motion, he should be consistently informed about the fact whether the brake line of the train is connected at full length, and whether also the last vehicle is actually following the train. it is accordingly a general object of the invention to provide apparatus to indicate the continuity in a pressure line.

Heretofore, systems have been proposed which generate decreasing pressure impulses at one end of the line and which sense for these impulses at the other end of the line.

Such a system is applicable to short trains, i.e. in trains with a comparatively short total length of the brake line, whereas it is inapplicable to long trains. This fact is due to a concurrence of two circumstances.

One is that the pressure drops must be increased in proportion to the length of the brake line, in order to make possible a measurable variation of pressure at the locomotive. In a long train, the pressure decreases at the last car must be made so large that the braking system of the train comes into operation, which is, of course, not permissible. Otherewise, however, no indications are to be obtained. The efliciency of the arrangement is therefore limited to such a degree that the system is not generally applicable.

The other circumstance is that the inclination of the front of an expansion wave is more and more flattened, the longer the distance is, over which the wave has to pass through a pipe. In a long train, the wave front will be very fiat when arriving at the first vehicle of the train and consequently very hard to indicate.

A more specific obiect of the invention is to provide a system in which increased pressure impulses are utilized.

It should be noted that this way of generating pressure variation impulses is accompanied by a number of advantages, resulting in an applicability of the system to trains of any conceivable length and also to systems utilizing pressure below atmosphere pressure for the braking, that is, vacuum systems. Thus, increases of pressure give rise to compression waves in the brake line, which, in contradiction to expansion waves are characterized by the fact that the wave front becomes steeper, the longer the brake line through which it has to pass. Contrary to decreased pressure impulses, increased pressure impulses can be given a magnitude necessary for causing an in dication without causing the train brakes to function. Another advantage is due to the fact that a compression wave, as mentioned, causes a steep variation of pressure at the front vehicle of the train, this circumstance making it possible to obtain an indication of even extremely weak impulses, this owing to the fact that it is easier to measure and thus to indicate a small but rapid variation of pressure than a slow one even if the latter is much larger.

According to the present invention the system com prises in combination an appparatus for producing increased pressure impulses in an air brake line of a train, and an apparatus for sensing the impulses in the brake line. The apparatus for producing the increased pressure impulses is preferably connected to the brake line of the last vehicle of the train and the apparatus for sensing the impulses is preferably connected to the brake line of the first car of the train.

Other objects, features and advantages of the invention will be apparent from the following detailed description, when read with the accompanying drawings, wherein:

FIG. 1 is a diagrammatic view of a train, FIG. 2 illustrates an exemplary embodiment of an apparatus for producing increased pressure impulses, and FIG. 3 is an apparatus for sensing increased pressure pulses in a brake line.

FIG. 1 is a diagrammatic view of a railway train having a first car 1 containing the engineers cab, a last car 2 and a plurality of cars 3 between the first and last cars of the train. Each of said cars has, as usual, an air brake line 4, the lines of all cars being connected together to a line extending through the entire train. To the brake line of the last car 2 an apparatus 5 for producing increased pressure impulses is connected via conventional coupling means. An embodiment of such apparatus being illustrated in detail in FIG. 2. The first car 1 of the train, containing an engineers cab, is provided with an apparatus d for sensing increased pressure impulses. Sensing apparatus 6 is connected to the brake line 4 of car 1 and comprising indicating means for indicating the presence of pressure impulses in the brake line. An embodiment of an apparatus for sensing the impulses is further illustrated in FIG. 3.

The apparatus for producing increased pressure impulses as illustrated in FIG. 2 comprises:

A cylinder body 11, having two cylinder bores 11a and 11b of different diameter encloses a movable double piston 1.3, the two parts 13:: and 131) each fit into bores 11a and lib respectively. The cylinder bore Ma and the piston part 13a enclose a cylinder chamber A which opens into a pipe 12 to be connected to the brake line 4- of the last car 2 of the train. The cylinder body it is provided with a head member 14, acting as a rest for a helical spring 15, actuating the piston 13 to the left as viewed in FIGURE 2 and being compressed as the piston 13 is moved to the right. A pipe connection 16, comprising a reduction control valve 17, connects the inlet pipe 12 to a cylinder chamber B enclosed by the cylinder bore lib and the piston. The piston part 13b having the greater diameter is equipped with a valve means consisting of apertures 19, 20, a valve member 21 and a helical spring 22. Apertures 19, 20 lead through the piston part 13b from the cylinder chamber B to a region C, enclosed by the cylinder head 14 which is connected to the atmosphere through an aperture 18.

The helical spring 22 tends to keep the valve member 21 in a position in which the valve is open. In one end position of the piston 13, the valve member 21 is actuated by a stop 23 to close the valve and at the other end position of the piston 13 by an adjusting screw 24- to open the valve.

The apparatus functions as follows:

When the piston 13 is in its left extreme position as viewed in the drawing under the iniiuence of spring 15, valve 21 has been shut oh" by the stop 23. It is then kept closed by the air pressure arising in chamber B by air entering from tube 12 through the pipe 16 and the con trol valve 17. Under the influence of the rising air pressure in chamber B, piston 13 is moving to the right while compressing the spring 15. When the piston has been moved so far to the right that the valve member 21 contacts the adjusting screw 24, the valve opens, thus leaving the air in the chamber B free to flow through the valve into region C and to the surrounding air through aperture lb. The piston 13 is thus released from the pressure appearing in chamber B and is left free suddenly to move to the left under the influence of the compressed spring 15' and against the pressure present in the chamber A. During this movement, valve member 21 is kept open by the helical spring 22. The piston 13 thus rapidly returns to its left external position, where the valve member 21 is actuated into closed position by the stop 23, whereafter the cycle is repeated.

The speed with which the piston is moved while compressing spring 15 may be adjusted by means of the reduction control valve 17. This speed should be comparatively low in order that the corresponding movement of the piston does not cause any perceivable variation of pressure in the brake line. The reverse movement of the piston, however, should be effected rapidly, so as to give rise to a rapid increase of pressure in the chamber A. Consequently, the apertures 19 and 2t) should be dimensioned so as to allow for a fast movement of piston 13 under the influence of spring 15.

By means of the adjusting screw 24, the length of stroke of the piston 13 and thus the magnitude of the increase of pressure in chamber A, may be set a desired value.

The apparatus for sensin increased pressure impulses generated by the apparatus 5 of FIG. 1, for instance as described in connection with FIG. 2, is exemplified by the following description of an embodiment thereof as illus trated in FIG. 3.

In this embodiment the apparatus consists of an enclosure 31, consisting of two halves 31a and 31!), between which a membrane 32 is arranged so as to divide the space within the enclosure 31 into two chambers D and B. By two curved tube pieces 33 and 34, the chambers D and E, respectively, are connected with the brake line 4 of a vehicle, in which an indication of presence in the brake line of impulses generated by apparatus 5 is to be displayed. The membrane 32- actuates, when being deflected under the influence of a pressure difference in the charmbers D and E, a contact means consisting of contact E1161 bars 35 and 36. The contact means is part of an indicatin electrical circuit, in FIG. 3 symbolized by an indicating lamp 3? in series with the contact means 35, 36 and a current source 38.

When increased pressure impulses are generated in the brake line of the last car of the train, said impulses propagate in the brake line as pressure waves with a steep wave front. The front angle increases in spite of the decreasing amplitude of the wave, and pass through the brake line i from the left to the right in PEG. 3 between the two tube pieces 33 and 34. Consequently, a higher pressure will suddenly appear in cham er D to the left of the membrane 32 than in chamber E, the pressure diference bringing the contact part 35 of the membrane 32 to contact for a short duration with the spring contact 36. Since lamp 37 and current source 38 are connected in series with the contact means 35, 36, the lamp 37 will be flashing in the same rhythm as the increased pressure impulses produced by apparatus 5 at the last car. This flashing will cease as soon as a cock in the brake line through the train is shut oil or if a part of the train, for some reason, is torn from the remaining train. The engineer wi l thus receive a continuous indication that the train is order.

The electrical indicating circuit as illustrated in FIG. 3 may be substituted for by means for causing a continuous indication of the presence of pressure impulses in the brake line, containing time circuits so dimensioned that indication will cease after a time, chosen with due respect to the impulse repetition rate of the pressure impulse generating apparatus. Circuits of this kind are well known to the art.

I claim:

1. Apparatus for generating periodically occurring increased pressure impulses in the brake line of a train wherein said brake line contains fluid under pressure, said apparatus comprising a housing for a chamber including first and second ends, conduit means at said first end for connecting said chamber to said brake line, piston means movable in said chamber between said first and second ends, said piston means including a projection extending into said conduit means for sealing oif said brake line from said chamber, first spring means for urging said piston means toward said first end to increase the pressure in said brake line, control valve means connecting said brake line to said chamber at said first end for transmitting a back pressure against said piston means for urging said piston means toward said second end, valve means in said piston means for connecting the region of said chamber between said piston means and said first end to the atmosphere, second spring means for urging said valve means open, means in said first end for closing said valve means with said piston means at said first end, and means in said second end for opening said valve means with said piston means approaching said second end whereby said valve means is open during the travel of said piston means toward said first end and is closed during the travel of said piston means toward said second end.

2. Apparatus for generating periodically occurring inreased pressure impulses in a line containing a fluid under pressure, comprising a first chamber including first and secondv ends, a first piston in said first chamber, said i rst piston being movable between the first and second ends of said first chamber, conduit means for connecting the first end of said first chamber with said line, spring means for urging said first piston toward said first end of said first chamber, a second chamber and a second piston movable in said chamber together with said first piston as a unit, pressure reduction means connecting said second chamber with said conduit means for providing fiuid pressure in said second chamber for moving said second piston and said first piston as a unit against the action or" said spring means, said first piston being thereby urged toward said second end of said first chamber, and valve means in a passage between said second chamber and the surrounding air, said valve means being open with said first piston at the second end of said first chamber and being closed with said first piston at the first end of said first chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,859,090 Holte May 17, 1932 1,869,020 Netteton July 26, 1932 1,891,655 Stewart Dec. 20, 1932 

1. APPARATUS FOR GENERATING PERIODICALLY OCCURRING INCREASED PRESSURE IMPULSES IN THE BRAKE LINE OF A TRAIN WHEREIN SAID BRAKE LINE CONTAINS FLUID UNDER PRESSURE, SAID APPARATUS COMPRISING A HOUSING FOR A CHAMBER INCLUDING FIRST AND SECOND ENDS, CONDUIT MEANS AT SAID FIRST END FOR CONNECTING SAID CHAMBER TO SAID BRAKE LINE, PISTON MEANS MOVABLE IN SAID CHAMBER BETWEEN SAID FIRST AND SECOND ENDS, SAID PISTON MEANS INCLUDING A PROJECTION EXTENDING INTO SAID CONDUIT MEANS FOR SEALING OFF SAID BRAKE LINE FROM SAID CHAMBER, FIRST SPRING MEANS FOR URGING SAID PISTON MEANS TOWARD SAID FIRST END TO INCREASE THE PRESSURE IN SAID BRAKE LINE, CONTROL VALVE MEANS CONNECTING SAID BRAKE LINE TO SAID CHAMBER AT SAID FIRST END FOR TRANSMITTING A BACK PRESSURE AGAINST SAID PISTON MEANS FOR URGING SAID PISTON MEANS TOWARD SAID SECOND END, VALVE MEANS IN SAID PISTON MEANS FOR CONNECTING THE REGION OF SAID CHAMBER BETWEEN SAID PISTON MEANS AND SAID FIRST END TO THE ATMOSPHERE, SECOND SPRING MEANS FOR URGING SAID VALVE MEANS OPEN, MEANS IN SAID FIRST END FOR CLOSING SAID VALVE MEANS WITH SAID PISTON MEANS AT SAID FIRST END, AND MEANS IN SAID SECOND END FOR OPENING SAID VALVE MEANS WITH SAID PISTON MEANS APPROACHING SAID SECOND END WHEREBY SAID VALVE MEANS IS OPEN DURING THE TRAVEL OF SAID PISTON MEANS TOWARD SAID FIRST END AND IS CLOSED DURING THE TRAVEL OF SAID PISTON MEANS TOWARD SAID SECOND END. 